1. Field of the Invention
The invention in general relates to electronic circuits, and more particularly to a high frequency microwave mixer with reduced noise and improved dynamic range.
2. Description of Related Art
A mixer is an electronic circuit which converts an input signal from one frequency to another. Basically, this is accomplished by combining, for example, an RF input signal with the signal from a local oscillator in a non-linear device, one example of which is a diode quad. As a result of the process, various frequencies are generated, including sum and difference frequencies. The difference frequency may be selected as the intermediate frequency (IF) for further processing.
In order to convert a wide range of input RF signals, from a maximum to a minimum, the mixer must have a wide dynamic range. Often this is accomplished by increasing the power or drive level of the local oscillator. Fabricating the mixer as an integrated circuit on a Si (silicon) chip requires that the local oscillator power be objectionably large. The present invention uses SiGe (silicon germanium) technology to provide a high frequency integrated circuit mixer having a wide dynamic range with relatively low power consumption. In addition, high linearity is achieved with a novel passive RF balun fabricated on the silicon chip.